X-ray examination apparatus with an X-ray source and a diaphragm unit connected thereto

An X-ray examination apparatus comprising:

• (a) an X-ray image pick-up device for picking up X-ray images;
• (b) a first source of radiation, said first source being a source of X-radiation including at least one focal spot for forming an X-ray radiation beam;
• (c) a second source of radiation forming a radiation beam;
• (d) a diaphragm unit which includes shutters which can be adjusted in position by means of a drive device in order to define an aperture size limiting the radiation beam formed by either the first source of radiation or by the second source of radiation;
• and
• (e) a control unit which controls the drive device, the control unit including means for causing the drive device to automatically move said shutters from a first position defining a first aperture size to a second position defining a second aperture size different from the first aperture size when the radiation beam changes between the first source and the second source, the first and second positions being such that the radiation field due to the X-ray radiation beam from the first source of radiation as limited by the first aperture size has the same size in the plane of the X-ray image pick-up device as the radiation field due to the radiation beam from the second source of radiation as limited by the second aperture size.